Helical-wound magnetostrictive line hydrophone



A r-i128, 1970 PARKER r 3,509,523

HELI CAL-WOUND MAGNETOS'IRICTIVE LINE HYDROPHONE Filed March 19, 1969 5 m mm mw rm .w m 7 Vw ah h j & Y

United States Patent Office 3,509,523 Patented Apr. 28, 1970 3,509,523 HELICAL-WOUND MAGNETOSTRICTIVE LINE HYDROPHONE David E. Parker, Pawcatuck, and Winslow W. Prentice, Waterford, Conn., assignors to the United States of America as represented by the Secretary of the Navy Filed Mar. 19, 1969, Ser. No. 808,575 Int. Cl. H04r 15/00 US. Cl. 34011 7 Claims ABSTRACT OF THE DISCLOSURE An acoustic free flooding hydrophone of a thin magnetostrictive strip formed into a closed loop and having a pressure release material against one surface thereof. An electrically conducting wire is continuously toroidally wound about said loop transversely and the entire loop structure is formed into a longitudinal double helix.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalities thereon or therefor.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to underwater communication and more particularly pertains to free-flooding line magnetostrictive hydrophones.

Description of the prior art In the field of underwater communication it has been the practice to employ transducers and hydrophones of the unitary and solid variety wherein the sensitive structure is relatively rigidly mounted and of a limited length. Such devices have been unsatisfactory in that their length and therefore their utility have been restricted. The present invention fills this need in that it can be economically fabricated in a continuous manner to provide any desired length.

SUMMARY OF THE INVENTION The general purpose of this invention is to provide a hydrophone that has all the advantages of similarly employed prior art devices and has none of the above described disadvantages. To attain this, the present invention provides a unique structural magnetostrictive line hydrophone which comprises a loop of nickel strip having a corprene coating on one side and a toroidal winding thereabout. The loop is then lengthwise wound as a double helix.

An object of the present invention is to provide a reliable, inexpensive and simple magnetostrictive line hydrophone.

Another object is to provide a free flooding line hydrophone which may be readily fabricated in any desired length and used with as many active elements as necessary.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the coated nickel strip with the winding,

FIG. 2 shows the strip of FIG. 1 formed into a closed loop,

FIG. 3 illustrates the completed hydrophone made in accordance with'the principle of this invention, and

FIG. 4 illustrates another technique for fabricating the loop hydrophone.

DESCRIPTION OF A PREFERRED EMBODIMENT In the illustrated embodiment of FIG. 1 a thin nickel strip 10 is provided with corprene coating 11 cemented to one face of the strip. Prior to the application of the corprene coating, which serves as a pressure release, the nickel strip is annealed at approximately 900 C. Clearly, any of the readily available well known pressure release materials could have been employed in place of the corprene. A relatively small diameter, insulated, waterproof Wire 12 is wound transversely about the strip for almost its entire length. The ends 13 and 14 of the strip are spot welded to each other so as to form the loop illustrated in FIG. 2 while the wire leads 15 and 16 extend from the welded portion of the loop. The loop is extended and wound as a double helix about some form or strength member 17, which may thereafter be removed if desired. The ends of the wire 15 and 16 are encapsulated in a Waterproof matrix 18 and therein connected to a waterproof cable 19 for coupling to a remote receiver.

Sensitivity measurements have been performed in the evaluation of the aforedescribed hydrophone for both with and without an applied DC. potential. The response curve indicates that the response is .relatively constant from 9 to 20 kc.

Alternately a wider nickel strip 20 with a corprene backing 21 could be slit as shown in FIG. 4 thus removing a lengthwise center portion but leaving the ends joined to form a closed loop. A waterproof insulated wire 22 is continuously wound about the separately formed strip portions 23 and 24. This configuration conforms to that of FIG. 2 and thereafter the double helix winding is fabricated as per FIG. 3.

We claim:

1. A magnetostrictive line hydrophone which comprises:

a closed loop of a thin strip of magnetostrictive material,

an insulated electrical conductor continuously wound transversely about said strip,

said loop and said conductor winding being formed into a lengthwise extended double helix, and electrical means connected to the ends of said conductor for coupling to a remote location.

2. The hydrophone according to claim 1 further including a layer of pressure release material affixed to one face of said strip.

3. The hydrophone according to claim 2 wherein said pressure release material is corprene.

4. The hydrophone according to claim 3 wherein said magnetostrictive material is nickel.

5. The hydrophone according to claim 4 further including a longitudinal strength member disposed coaxially with said helix.

6. A method for fabricating a magnetostrictive line hydrophone which comprises the steps of:

winding an insulated electrical conductor transversely about a ribbon of magnetostrictive material,

joining the ends of said ribbon to form a closed loop,

double helically winding said loop, and

coupling the ends of said conductor to a remote location,

7. A method for fabricating a magnetostrictive line hydrophone which comprises the steps of:

removing a central lengthwise extending portion of a 4 References Cited UNITED STATES PATENTS 3/1965 Wollett 340-11 3/1953 Thuras 340-11 RODNEY D. BENNETT, Primary Examiner B. L. RIBANDO, Assistant Examiner 

